Why would Nvidia care about supporting Wayland at this point in time? Steam itself doesn't even work properly with Wayland. 9 of 10 people are going to be using X right now and within the near future.

Wayland offers performance and security improvements over X, and is seeing rapid adoption on GNOME-based distributions. Since both Intel and AMD properly support Wayland through the GBM buffer API, Nvidia is going to be left behind unless they start improving or replacing their EGLStreams API instead of leaving it stagnant.